Methods of molding generally are well known. Conventionally, a molded part is made by providing, e.g. via injection, pouring or other suitable or conventional means, an uncured molding compound into a molding cavity whose shape and surface contour conform to the desired shape of a finished molded product. As supplied to the mold, the molding compound generally is in liquid form so that it can flow and conform to the shape, and fill the volume of, the molding cavity. The molding compound then is caused or permitted to cure or harden or solidify, thus producing a greenware solid part conforming to the shape and contour of the molding cavity. The greenware part is demolded, and often is subjected to some subsequent treatment, such as a heat treatment, to impart additional strength to the part prior to use. Alternatively, for some molding compounds the demolded greenware part immediately is ready or suitable for use without any subsequent treatment.
By way of example, molding compounds of interest include ceramic compounds, and particularly alumina compounds. In one conventional operation, a mold for a ceramic part includes two mold halves wherein each half includes a respective molding cavity half. During a molding operation, the mold halves are adapted to be joined together or brought into contact such that the molding cavity halves provided respectively therein cooperate to form a substantially continuous molding cavity having a seam defining the perimeter of the cavity adjacent the line of contact between the cavity surfaces of the respective molding cavity halves. An injection port can be provided in either or both of the mold halves in order to deliver the molding compound into the molding cavity once the halves have been joined. Alternatively or additionally, each mold half can be provided with a respective runner in the form of a groove in the facing surface of each mold half (the surface that will mate or join the corresponding surface of the opposing mold half to provide the complete molding cavity during a molding operation), such that when the mold halves are joined (facing surfaces brought into contact) the respective runners cooperate to define a complete injection port to deliver ceramic molding compound into the molding cavity.
Unfortunately, it is not uncommon for injection ports or for the runners that define an injection port to become clogged or backed up with a residue of the molding compound. Often it is necessary for an operator manually to apply a mold release agent such as a silicone agent to the runners, or otherwise to flush the injection ports with such an agent, between molding operations in order to ensure the injection ports are free of debris. A significant problem associated with this is that different operators can employ relatively inconsistent techniques for applying the mold release agent to the runners, or, flushing the injection ports. This can result in inconsistent and unpredictable amounts of mold release agent being applied between successive runs for making molded parts. Too little release agent can result in improper or impeded injection of molding compound due to blockage; too much can damage or ruin batches of subsequently molded parts.
In addition, molds for some parts have regions of highly intricate surfaces where mold release often is a problem. It is usual for an operator to apply to such regions a quantity of mold release agent between successive runs of making the molded parts in order to facilitate effective release from such regions. However, here too the quantity, as well as the layer thickness, of mold release agent can be highly variable and unpredictable depending on the operator's technique, leading to inconsistent application of mold release agent and unpredictable results between successive runs.
There is a need in the art for an apparatus and method effective to reproducibly apply a metered quantity of a mold release agent at desired locations along a molding surface, and particularly at the injection ports.